Dual Purpose BIAC Control Panel

[Jcruse]

I've had a medium Brewha BIAC sitting in my garage unassembled for 5 years (kids/business/life), and it's finally time to build this thing. At the time I also ordered a ton of parts to build a control panel for it. I remember I pretty much had the panel design figured out, but being 5 years ago I can't find my design files and have no recollection of the design.

My main goal with the panel is to be not only the brew day controller, but also the fermentation controller, since you use the same vessel for everything. This raised some unique challenges (as I really wanted to use the EZBoil PID controller for the brewing controller, but I don't believe it has any cooling capability. I also wanted to be able to program fermentation stages with the controller (step temperatures for lagers, cold crashing, etc.). So in addition to an EZBoil PID I also bought an Auber SYL-2352p PID that has step programmability. If I didn't already have almost all the parts already, I would probably just buy the Brewha touchscreen controller that does exactly everything I'm wanting. I also enjoy the challenge of trying to build something myself.

I've attached my first stab at a diagram for the panel to see if I could get the group to review and provide feedback. The main differences between this panel and other BIAC control panels is that instead of a Element on/off switch, I have a "Brew Mode" 3-way switch that can switch between BREW, OFF, and FERMENT. By switching between these settings, it will power on the appropriate PID, and alter the voltage to the 5500 watt element (240v for BREW, and 120v for FERMENT). In essence it's almost 2 controllers in one box, with separate PID/SSR/ELEMENT CONTACTOR chains for each mode.

The design points I'm really looking for feedback on are the shared outlet for the element for both modes, and the need for an e-stop button. I could always add a 2nd receptacle for the fermentation mode, but I don't really think it's necessary, since only one contactor that supplies power to the element can be closed at a time. Also I don't have an emergency stop in the design currently. I know there used to be a lot of argument about how those should be wired, but if it's needed, I'm leaning towards the design that trips the GFCI breaker at the distribution panel (because if your main contactor fails and arc-welds itself together in the closed position, turning the main switch to off or pressing an e-stop button that is wired to the contactor coil will NOT cut power to the panel). The e-stop wouldn't be a way to quickly shut things off if you have a brewing failure like a boilover, but only a last-ditch resort during catastrophic electrical failure. Finally, I didn't really make any attempt to accurately model how the PID's will be wired up (I know the line in, SSR signals are all in the wrong place, there's no temp probe in the diagram, etc...)

Anyway, let me know what you think, and thanks!

 

[stamandster]

Though a PID to control fermentation seems overkill, you could put a center off three way DC switch on the PID control voltage side to a single 40a SSR and contactor. This is how I switch between a Boil controller with knob and a PID, and it works well. Doing so you'll save money and complexity.

 

[doug293cz]

I think your design concept is more complicated than it needs to be. A single SSR is all you need to control power to the element. You put a 1NC/1NO relay/contactor in to chose whether hot2 or neutral goes to the element outlet, and control that relay/contactor with your selector switch. Here's a design that does this:

If you have a main power contactor, and separate contactor(s) for element power enable, then if properly operated (element contactors off, pumps off, etc. before the main power contactor is switched on or off), less than 1 amp current will be switched by the main power contactor points. You will never "arc weld" the contacts together with this low current. So, you can follow normal industrial practice and have an e-stop just cut power to the main power contactor coil. You will probably get some arcing if hitting the e-stop when operating with a high current draw, but the contacts will be separated before the arcing occurs. It is also fairly easy to implement a "safe-start" interlock that prevents main power from being turned on if any of the element enable switches, pump switches, etc. are in the on mode when trying to power up.

Personally, I question the value of an e-stop mushroom button on the control panel enclosure, since you have a main power switch right there. E-stops in industrial situations are located remote from the control panels, where operators are likely to be if an emergency condition arises. However, if it makes you feel better, go ahead and put one in.

You could control both heating and cooling with a single EZBoil DSPR320. You would use one of the "alarm" relays to control the coolant pump. You would have to set the "over temp" alarm trip point manually for each fermentation step, as I don't believe you can pre-program the OT trip by program step.

Brew on